Duquesne Advanced General Biology I Exam II

phospholipids are considered to be _______ molecules

amphipathic

Definition of amphipathic

having both hydrophilic and hydrophobic parts

what forms spontaneously in solution?

bilayers

what is the permeability of bilayers?

selectively permeable

molecules spontaneously diffuse from what to what concentrations?

high to low

what are membrane proteins responsible for transporting across the membrane?

ions, polar molecules, and large molecules

definition of cell membrane

a double layer of molecules that surrounds the cell, separating it from the environment and selectively regulating the passage of molecules and ions into and out of the cell

another term for the cell membrane

plasma membrane

why was the evolution of a barrier such an important development?

chemical reactions required for life could occur more efficiently in an enclosed space

what is the last major type of mid-sized molecule found in cells?

Lipids

What keeps your eyes from dehydrating?

a lipid layer

what are 2 examples of lipid function?

ear wax and eyes

what are the layers of the eyes from inner to closest to the outside?

cornea, mucin layer, aqueous layer, lipid layer

what do lipids form in a solution?

water filled vesicles

what cells resemble vesicles?

red blood cells

what is isoprene

hydrophobic building block for many large molecules

isoprene is a building block for what common molecule, but not for what other common molecule?

cholesterol, not fatty acids

what are fats?

a type of lipid found in cells

how are fats formed?

dehydration reactions

what are fats made of

a glycerol linked by ester linkages to 3 fatty acids

are fats polymers

no

are fatty acids monomers

no

are fatty acids used to build fats?

yes, triglycerides

what are lipids defined by?

a physical property (solubility)

what are lipids specifically NOT defined by?

chemical structure

what is the structure of a phospholipid?

a glycerol backbone connected to a phosphate group and two fatty acids

are Achaea phospholipids the same as the phospholipids of bacteria and eukarya?

no

what are three ways archaea phospholipids differ from those of bacteria/eukarya?

archaea phospholipids have branched isoprene chains while bacteria and eukarya have unbranched fatty acids, archaea have ether linkages while bacteria and eukarya have ester linkages, and archaea phospholipids have L-glycerol while bacteria and eukarya have D-glycerol

where is the double bond in an L-glycerol?

Low

where is the double bond in a D-glycerol?

high (Like where Disco ball is hung from)

can hydrocarbons H-bond with water?

no

because lipids can not dissolve in water, what happens instead?

2 types of structures form spontaneously

what are the two structures that form spontaneously from lipids in water?

lipid micelles and lipid bilayers

what is a lipid micelle?

a vesicle of lipids with shorter tails and no water inside

what is a lipid bilayer?

lipids with longer tails facing each other that has no water between lipids, but water inside and outside of the bilayer

what specific part of phospholipid nature is important for biological function?

amphipathic/duo nature

liposomes

artificial membrane bound vesicles

planar bilayers

artificial membranes

formula for SDS (Sodium Dodecyl Sulfate)

Na⁺C₁₂H₂₅SO₄⁻

what is SDS

a common detergent

amphipathic molecule

a long hydrocarbon tail with a hydrophilic negatively charged end

what molecules can easily go through a selectively permeable membrane?

small nonpolar molecules

can large molecules and uncharged substances cross a membrane unfacillitated?

yes, BUT slowly if at all

what do unsaturated hydrocarbons have that saturated hydrocarbons do not?

carbon to carbon double bonds

how do C=C double bonds affect shape of hydrocarbons?

they create a kink

what does the C=C double bond do to a molecule

confines it to one plane

how do unsaturated fatty acids affect the permeability and structure of a membrane?

they make the membrane more permeable and more fluid

how does cholesterol affect permeability of a membrane?

it decreases the permeability 

true or false: phospholipids are still within membranes

false

phospholipids are in constant __________ movement but never ____________

lateral, flip to the other side of the bilayer

Definition of diffusion

constant random movement of molecules from kinetic energy

definition of osmosis

diffusion of water 

how does a hypertonic solution outside of the cell affect the cell?

net flow of water out of the cell, cell shrinks

hypertonic solution definition

more solute within the solution

hypotonic solution definition

less solute within the solution

isotonic solution definition

same amount of solute within the solution

how does a hypotonic solution outside of the cell affect the cell?

net flow of water into the cell, cell swells or even bursts

how does a isotonic solution outside of the cell affect the cell?

no change

integral proteins

membrane proteins that go through the membrane

peripheral proteins

membrane proteins that do no go through the membrane but instead are bound to integral proteins or that have lipids attached to them

gradients can be ___________ or ____________

chemical or electrochemical

definition of facilitated diffusion

diffusion via highly selective ion channels that requires no energy

passive transport

transport of molecules or ions along a concentration gradient that requires no energy/ATP

active trasport

transport of molecules or ions against a concentration gradient that requires energy/ATP

What two elements of cell components are closely connected to each other

Structure and function 

what do cell materials need in order to be transported to their destination

molecular zip codes

True or false: chemical reactions occur one at a time

false, many chemical reactions occur per second

true or false: molecules occasionally cross the membrane

false, molecules constantly cross the membrane

cell products are shipped along __________

protein fiber highways

true or false: components of the cytoskeleton never change size

false, components of the cytoplasm such as internal beams and grinders grow and shrink

true or false: unicellular organisms outnumber multicellular organisms

true

true or false: prokaryotic cells are essentially a loose sac of organelles floating freely

false, prokaryotic cells are highly organized

what are the 2 major types of prokaryotic cells

gram negative and gram positive

what do gram negative cells have that gram positive cells do not

A second membrane outside of a thinner cell wall

true or false: most prokaryotes have half the number of chromosomes as a eukaryotic cell

false, most prokaryotes have one single circular chromosome

where are bacterial ribosomes within the cell

cytoplasm

Internal membranes are __________ in bacteria, except for _____________, which occurs because ____________

not common, except for the extensive folding of membranes in photosynthetic organisms, stacked infoldings of the plasma membrane have enzymes and pigments required for photosynthesis

How do the structures of Prokaryotic and Eukaryotic cells differ?

Location of DNA, internal membranes and organelles, cytoskeleton, and size

Where is the DNA located in prokaryotes

in the nucleoid or plasmids

where is DNA located in eukaryotes

inside the nucleus, plasmids are extremely rare

how do organelles and internal membranes differ between prokaryotic and eukaryotic cells

prokaryotic cells have limited types and numbers of organelles and extensive internal membranes are only in photosynthetic species. eukaryotic cells have large numbers and types of organelles

what is the cytoskeleton like in prokaryotes relative to eukaryotes

limited in extent

what is the cytoskeleton like in eukaryotes

extensive, usually found throughout the volume of the cell

are prokaryotes or eukaryotes generally larger

eukaryotes are typically about 10x the size of prokaryotes in diameter and 1000x larger in volume

what is something an animal cell has that plant cells lack

centrioles

what are two things that plant cells have that animal cells lack

cell wall and chloroplasts

where are proteins sythesized

ribosomes

what translates soluble proteins

cytoplasmic ribosomes

what is the rough ER

a protein synthesizing and processing complex

what translates secreted proteins

rough ER ribosomes

which face of the golgi is oriented towards the rough ER

cis

where is the trans face of the golgi oriented towards

the plasma membrane

true or false: the golgi has polarity

true

what is the golgi the site of

glycosylation

what happens in the smooth ER

lipid and phospholipid synthesis

peroxisomes are the sites of _____________

oxidation reactions

how does peroxide from oxidation reactions not damage the cell?

it is contained to limit cell damage

what are lysosomes

recycling centers of the cell

what happens in a lysosome

degradation of proteins, lipids, nucleic acids, and carbs

true or false: lysosomes are uniform 

false, they vary in shapes and sizes